Five years ago, airlines began charging passengers for any extra bags they checked. Then, with the notable exception of Southwest Airlines, which constructed an ad campaign around the slogan “bags fly free,” the airlines began charging for even the first bag.

It seems to have paid off. The revenues from checked bag charges rose from $464 million in 2007 to over $2billion last year. And aside from the money there were other benefits as well. According to The New York Times, passengers checked fewer bags, thus few bags were lost; the cargo holds could be loaded and unloaded more quickly; baggage handlers suffered fewer injuries; and there was more room in the hold for more lucrative freight.

The charge for checked bags had foreseeable consequences in the war of wits between airlines and their customers. The passengers wrestled ever larger and heavier bags into the cabin as carry-ons. Instead of the baggage handlers getting injured, it was the flight attendants from trying to stuff oversized bags into the overhead compartments. The time saved in the cargo hold was more than lost at the gate trying to get the passengers and their carry-ons settled.

The next step was inevitable. Starting this summer, Spirit Airlines will charge $30 – $45 at the gate – for carry-on bags too big to fit under the seat. The economics of this are curious. Spirit, which bills itself as the leading Ultra Low Cost Carrier in this part of the world, charges only $20.98 for some flights, meaning it would be cheaper to buy your bag a ticket for the seat beside you.

And where will the airlines go from here? Ryanair, a low-cost European carrier, plans to eliminate checked baggage altogether on certain flights. One of the airline’s executives told the Times that people pack too much stuff anyway.